RIVIERA BEACH, FL—Stereotactic laser ablation is an attractive option for the treatment of refractory temporal lobe epilepsy, according to an overview presented at the 42nd Annual Meeting of the Southern Clinical Neurological Society. Compared with temporal lobe resection, laser ablation is less invasive and is associated with a similar rate of seizure freedom at one year. Recovery from laser ablation is rapid, and patients generally return to work in a few days.
The technique entails fewer postsurgical cognitive complications than resection does, perhaps because laser ablation does not affect the fiber tracts that connect mesial temporal structures to the neocortex. At some of the centers that perform this procedure, however, patients who underwent laser ablation had postsurgical visual field cuts. Unintentional damage to the lateral geniculate nucleus could explain this outcome, said Andres M. Kanner, MD, Director of the International Comprehensive Epilepsy Center at the University of Miami Miller School of Medicine.
Furthermore, psychiatric complications, including recurrence or exacerbation of mood or anxiety disorders, are approximately as common after laser ablation as after resection. These complications may require pharmacologic intervention or hospitalization.
MRI Guides the Surgery
Laser ablation initially was performed to treat brain tumors and also has been used in general surgery. The technique uses thermal therapy to necrotize or coagulate soft tissue. A typical workstation for laser ablation readily interfaces with MRI, which enables the neurosurgeon to guide the 15-W laser. The laser applicator is 1.65 mm in diameter and includes a cooling catheter and a laser-diffusing fiber. The laser itself is 980 nm in diameter. Software predicts the amount and extent of tissue damage in real time.
In patients with treatment-resistant temporal lobe epilepsy, the goal of the surgery is to ablate the mesiotemporal structures, including the amygdala and the hippocampus. The neurosurgeon inserts the probe through a 2-mm burr hole in the occipital region of the patient’s skull. During ablation, software calculates the temperatures in the mesiotemporal regions, which allows the neurosurgeon to operate with precision.
Freedom From Disabling Seizures
Jonathan Jagid, MD, the epilepsy neurosurgeon at the University of Miami Epilepsy Program, has performed laser ablation for 25 patients since November 2013. To minimize the risk of postsurgical psychiatric complications, patients are evaluated for past and current psychiatric disorders. Patients with a current mood or anxiety disorder receive treatment before surgery.
The Epilepsy Surgery Program of the University of Miami has at least six months of follow-up data for 18 of the 25 patients who have undergone laser ablation. Follow-up visits occur at one week, four weeks, 12 weeks, 24 weeks, 36 weeks, 52 weeks, and every six months thereafter if patients are seizure-free. At each visit, the neurologists record seizure frequency, cognitive and psychiatric symptoms, and adverse events of antiepileptic drug therapy. The high frequency of follow-up enables the neurologists to monitor patients for postsurgical psychiatric changes, said Dr. Kanner.
Of the 18 patients, 10 were male. Mean age was 42, which is slightly older than in most series of temporal lobectomy, said Dr. Kanner. Seven patients were older than 50, and one was age 70. The site of ablation was in the left hemisphere for 10 patients and in the right hemisphere for eight patients. The mean follow-up period was 17 months, and the range was from seven to 25 months. The duration of hospital stay was two days.
Thirteen patients (72%) had an Engel Class I outcome, or freedom from disabling seizures. Six of these patients were completely seizure-free, and six had nondisabling seizures. One patient had a seizure following withdrawal from antiepileptic medication and became seizure-free when he resumed medication. Two patients had an Engel Class II outcome, or rare disabling seizures. Two patients had an Engel Class III outcome, or more than 90% improvement. In one patient, the surgery had no effect.
Cognitive and Psychiatric Outcomes
Neuropsychologic data were available for 10 patients, all of whom were right-handed and left-hemisphere dominant for language. Of these 10 patients, eight had an Engel Class I outcome, one had an Engel Class II outcome, and one had an Engel Class III outcome. Four patients with a dominant ablation had a decline in verbal memory, compared with presurgical baseline. One patient with a nondominant ablation demonstrated a decline in facial memory. Performance on measures of confrontation naming and phonemic and semantic word fluency was unchanged or improved for all patients. “That is a big advantage because one of the complications of temporal lobe resections in the dominant hemisphere is that patients develop word-finding problems” that can be disabling, said Dr. Kanner.